I defaulted everything to private and explicitly declared my shared's. Now what happens is that the outer "k" loop never gets incremented.

Even if I run with only one thread, "k" always equals 1.

So the snippet of code follows. Where m_ex and m_ib are parameters in Fortran and are hard-coded as numbers by the compiler.

If I compile with -fopenmp it works fine, but at the -fopenmp and "setenv OMP_NUM_THREADS 1" and it won't increment.

Any new ideas? Thanks in advance.

-Scott

!$OMP PARALLEL DO DEFAULT(PRIVATE) SHARED(mask,ibonly,ax,ay,az,

!$OMP& agxx,agxy,agxz,agyy,agyz,agzz,

!$OMP& aKxx,aKxy,aKxz,aKyy,aKyz,aKzz,nx,ny,nz)

!$OMP& SCHEDULE(STATIC,chunk)

do k = 1, nz

write(msg,*)' setbkgrnd: ' //

& 'nz = ',nz,', % done = ',int(k*1.0d2/nz),' '

call writemessage(msg)

do j = 1, ny

do i = 1, nx

if (mask(i,j,k) .ne. m_ex .and.

& (ibonly .eq. 0 .or.

& mask(i,j,k) .eq. m_ib)) then

x = ax(i)

y = ay(j)

z = az(k)

include 'gd.inc'

include 'kd.inc'

agxx(i,j,k) = gxx

agxy(i,j,k) = gxy

agxz(i,j,k) = gxz

agyy(i,j,k) = gyy

agyz(i,j,k) = gyz

agzz(i,j,k) = gzz

aKxx(i,j,k) = Kxx

aKxy(i,j,k) = Kxy

aKxz(i,j,k) = Kxz

aKyy(i,j,k) = Kyy

aKyz(i,j,k) = Kyz

aKzz(i,j,k) = Kzz

else if (mask(i,j,k) .eq. m_ex) then

c Excised points

agxx(i,j,k) = exval

agxy(i,j,k) = exval

agxz(i,j,k) = exval

agyy(i,j,k) = exval

agyz(i,j,k) = exval

agzz(i,j,k) = exval

aKxx(i,j,k) = exval

aKxy(i,j,k) = exval

aKxz(i,j,k) = exval

aKyy(i,j,k) = exval

aKyz(i,j,k) = exval

aKzz(i,j,k) = exval

endif

enddo

There is no explicit OMP END DO statement because it's optional.

--
Scott H. Hawley, Ph.D. Asst. Prof. of Physics
Chemistry & Physics Dept    Office: Hitch 100D
Belmont University    Tel: +1-615-460-6206
Nashville, TN 37212 USA    Fax: +1-615-460-5458
PGP Key at http://sks-keyservers.net

On May 18, 2011, at 4:37 PM, Scott Hawley wrote:

Erik, Frank, Peter: Thanks guys. I will pursue your suggestions.

--
Scott H. Hawley, Ph.D. Asst. Prof. of Physics
Chemistry & Physics Dept        Office: Hitch 100D
Belmont University                  Tel: +1-615-460-6206
Nashville, TN 37212 USA            Fax: +1-615-460-5458
PGP Key at http://sks-keyservers.net

On May 18, 2011, at 12:14 AM, Peter Diener wrote:

Hi Scott,

On Tue, 17 May 2011, Frank Loeffler wrote:

Hi,

On Tue, May 17, 2011 at 03:02:00PM -0700, Scott Hawley wrote:
Do these all be need to be declared as private?

If the temporary variables are declared only inside the loop they are
automatically thread-local. Oh wait, that is Fortran. Well - in that
case you should either declare all private, or (maybe easier) put the
include files into separate functions, declare the temporary variables
only there and call the functions from within the loop, in which case
they also don't have to be specified for openmp (as long as they are not
static).

i certainly don't want the various processors overwriting each others'
work, which might be what they're doing. -- maybe they're even
generating NaNs which would slow things down a bit!

Alternatively you may use the DEFAULT(PRIVATE) clause, so that you only
have to specify the shared variables. However, in that case you have to
make sure to really declare all the shared variables as shared, since
otherwise all processors will have to allocate storage and if they are 3d
variables this will slow down the code and increase memory consumption.
Also private variables have undefined values on entry to the parallel
region so not declaring all shared variables properly can also adversely
affect the result. So be careful.

You should see that in the results though. It might make sense to first
make sure that the results with different numbers of threads are the
same (depending on the problem you might actually get bit-by-bit
identical results), and work on optimization later. I agree that your
slow-down actually points towards some bug.

Frank

Cheers,

Peter

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